LED Colour Temperature Guide: 2700K, 4000K or 6500K?

Specify the wrong colour temperature on a lighting job and you'll know about it when the client calls. A kitchen that feels like a hospital. A bedroom that's too cold to relax in. A retail display that makes the products look grey.

Colour temperature is measured in Kelvin (K). Lower number = warmer, more orange. Higher number = cooler, more blue-white. This guide covers the four main temperatures you'll encounter on UK domestic and commercial work — and where each one belongs.

2700K — Warm White

2700K is the closest LED equivalent to traditional incandescent and halogen light. The light has a warm, amber quality that most people associate with comfort and relaxation.

Where to use 2700K:

• Living rooms and lounges — the standard domestic specification
• Bedrooms — warmth aids sleep and relaxation
• Hallways and stairs — welcoming, not harsh
• Hotel rooms and hospitality spaces
• Restaurants and bars where ambience matters
• Any space where the client wants the light to feel "homely"

Most residential downlighting and 2700K GU10 lamp replacements should default to 2700K unless the client or architect specifies otherwise. It's the safe choice for anything living-area related.

3000K — Warm White (slightly cooler)

3000K sits between 2700K and 4000K — still warm, but with a cleaner, crisper quality. Less amber, more white.

Where to use 3000K:

• Contemporary interiors where 2700K feels too yellow
• Retail — fashion and homewares where warm but accurate colour rendering is needed
• Bathrooms and en-suites — clean without being clinical
• Decorative filament lamps where traditional appearance is wanted with slightly better colour

3000K is increasingly the preferred temperature for high-end domestic installs and hospitality projects. If a designer or interior architect is involved, expect a 3000K spec more often than not.

4000K — Cool White (Neutral)

4000K is neutral white — clean, bright, no strong warm or cool cast. It renders colours accurately without the blue tone of daylight temperatures.

Where to use 4000K:

• Kitchens — the standard specification for task lighting over worktops
• Offices and commercial spaces
• Garages and utility rooms
• Classrooms and healthcare environments
• Retail where colour accuracy matters
• Bathrooms where a clinical, bright feel is wanted

4000K is the workhorse for commercial and functional domestic spaces. If you're fitting GU10 LED lamps in a kitchen, 4000K is the right call in most cases unless the client specifically asks for something warmer.

6500K — Daylight White

6500K is the coolest common LED temperature — a blue-white light that mimics outdoor daylight. It looks very different from warm white on the wall.

Where to use 6500K:

• Jewellers and display counters where colour critical accuracy is needed
• Food preparation and butcher display (makes meat look fresher)
• Workshops and technical work areas
• Security lighting where brightness and visibility take priority over comfort
• Some retail environments where a stark, modern aesthetic is intentional

Where NOT to use 6500K: Domestic living areas, bedrooms, most offices, and anywhere clients will spend extended time. It's frequently specified incorrectly for kitchens — 4000K is almost always better there. If a client has 6500K lamps in their kitchen and finds it uncomfortable, swapping to 4000K will fix it instantly.

Quick Reference

CRI: The Other Number That Matters

Colour Rendering Index (CRI) measures how accurately a light source renders colours compared to natural daylight. CRI 100 is perfect (halogen achieves this). Most LED lamps are CRI 80+, with premium lamps at CRI 90+.

For most domestic and commercial work, CRI 80 is adequate. For retail, galleries, healthcare and anywhere colour accuracy is critical, specify CRI 90+ and check the product data sheet before ordering.

GU10 LEDs in Stock at APM

We stock GU10 LEDs across the main colour temperatures — 2700K, 4000K and 6500K — from Integral LED, Meridian and Orlight. Dimmable and non-dimmable options available; matching dimmer switches are also available.

The Orlight CREE GU10 dimmable is a strong trade buy — CREE chip, consistent colour, reliable dimming performance.

APM Plumbing & Electrical Supplies
24 Western Avenue, Acton, London W3 7TZ
📞 020 8702 8080 | 🌐 apmi.uk
Mon–Sat, trade counter open. Contact APM for help choosing the right colour temperature.